Such regulation functions as cutting off, diversion, reflux resistance and flow splitting are required in a fluid conveying system. A valve is one of major devices for realizing these functions. Through long-term improvements and innovations, a plurality of forms of valves have been developed, such as a sluice valve, a needle valve, a dummy valve, a butterfly valve, a plug valve and a ball valve. The valves of these forms differ in structure in numerous ways, but in summary, it is apparent that there is not a big difference in their nature. It is mainly reflected in two aspects: on one hand, with respect to a flow control unit, a valve core device is mostly arranged in a fluid passing direction or in an axial direction of a cavity for each of those valves and the valve core is used for realizing the regulation of flow rates and open and close states; on the other hand, with respect to an operation unit, a device is mostly arranged in a radial direction of a pipeline or outside the pipeline for each of the valves to realize control on states of the valve core. In this way, no matter which type of valve is used, a common aspect is present, i.e., a pipe wall is broken by the connection of the operation unit outside the pipeline and the valve core, leading to that the pipeline itself is not in a closed state. In severe working condition environments, such as corrosion, high temperatures or high pressures, as time goes by, the above-mentioned features are prone to cause leakage at a position in the pipeline where a control mechanism passes through the pipeline. This is one of important problems urgent to be solved in the field of valves at present.